Safety device for pipettes



May 16, 1944. w. 1-. MATHIS SAFETY DEVICE FOR PIPETTES Filed Feb. 27, 1941 5 5 H. e Mm b 7. 5 1. O W Y 1.. 1 m A a M w flab f WM% m w I 1% 1 7 o 1 7 v! ..A a Q 0 v w M0 m 7/ 1 w a c 0 mm w w BA 5 u U M n W" 3 w m 6 5 7 v 2 1 1 qn w m 4 U V w V M 1 2 v Q71 0% 5 a w w n. Emu B m m u 1 2 ..I :5 m3: Is; I: I: S \j W membrane mumm es w'aad' rqtfani s', Clay Adams Co. I ration of York A.niiiicanmi.niiiiiamgza, 1941;; Sofia-111810;: 386.11.791- 1's Clai'msi" (01.22pm) This invention. relatesv generally to pipettesanglsimilar laboratoryapparatus. More particularly}; my invention is directed toward an improvedlandnovel safety device for use with pipettes 012th: like".

It is well known that in .usingpipettes for. meas. uring, transferring or.collectingrliquids,,the cu tomary practice is to draw. the .liquidinto the pipette by means of suctioncreatedhy the mouth; Since the liquids in connection with which these pipettes are used are often, ofa,poisonous.;o 1f... otherwise injurious nature it is obvious that this practiceof sucking. in the lidu'id's'is fraught.-With.-. great danger because the liquid is .apt, to bein advertently drawn into theimouth. of,the.. user.

It is therefore one of the objects ofm'yj haven-. tion to provide a safetywdeviceior .pipettesand thelike having certain novel and -ii'rinf0ve.d-.Q0nl-.,. structional features whereb ,theQabove d ,cribe'd'. dangers attending the customary. usenof pipettesll will be prevented. g M

Another object. of my invention, istogp'royide. a pipette safety device of the chaiacterwdescrjibed" which shallbe simple in construction, and..op,era:.. tion and which at the' same time shallbe efficient... and practical in use.

Other objects of my inventiori willjnfp'art. be obvious and in part hereinafterpointed out.

In' the accompanying drawing, 1 v i U Fig. l is an elevationaljview .of.a' pipette and safety device therefonconstructe'd in accordance with my invention; M

Fig. 2 is an enlarged vertical.crosssectional... view of the said safety device. and a portion. of .L said pipette;.

Fig. ,3 is a fragmentary viewof the device shown in Fig. 2, but illustratin the action thereof;

Figs. 4 and 5 are cross-sectional .viewssimilar: to Fig. 2, but showing modified formsiofmy'in- 40 vention; and V e I Fig. 6 is a cross-sectional view taken substa tiallyon theline B6 ofFig .5.

Referring now in detail to the drawing th e is. shown a pipette or tube lllwhich may he any suitable standard construction and adapt for use as a piece of laborator apparatu measuring, transferring or, collecting: liquidsthe wellknown manner. As- .hereinbe-fore:- d scribed, the customary, practice in: using-,;.t e pipette is to create a suctionlin;;the tubebylthc mouth of the userto draw. in the liquid.1;;1n.1:a -I, cordance with myinvention :I hav ,=.provided safety device l I for automatically.preventingrt liquid which has been drawninto the :tubeA 'DJES from coming-into contact with .theflips'or enter; 1

ing themouthiof the'user. 1

Th'e'said, device I I maybemadeof anysuitaniea: material such as rubber, Bakelite or the likexandr comprise's an attachment member-l2 having a bottomope'ning" 13 into :which there is rigidly attacheda resilient sleeve 14 [designed ,to' frictionally receive and. hold therein the: upper open end oflthe tube. H] as clearly shown in Fig; 2 of the. drawing. To'facilitate the creating of a suction inlthe tube.v l0, by:means-of the mouththere. 1

is .providedaa mouthpiece |5. COI np1iSing, an up-- wardly extending nipple-"shapedportion I51: and

and-nternally-threadedopening [6 in the top of the member It. A suitable packing memberll interposed between the base-J 51) of the nipple 1:15. andthe member l2 renders the connection leakproof,

Asshowninthedrawing the, mouthpiece i5 is provided with a vertically disposed through aper tureflflterminating -at the top in a countersunk *portionlfld, communicating with the surrounding atmosphere and communicating at the bottom thereofwiththe. opening; 16 in the memberv l2. The. .tr ansverse wall. 12a of the member I2 is also providedwith an. aperture ZI communicating with the openings I3 and l6 to thereby form a 'contir ous airpassagewa from the mouthpiece, 15 to the tubelll.

It ,is. noted thatuthe depending, shank 5 is spaced .a predetermined distance from the trans-v -verse walLJ 20 .to provide va chamber, A.

Disposedwithin the chamber A and overlying,

the apeitl res 20 and 2! are] a pair of mats or washer members .22 and .23; A spring 25 inter; posed between the said members.22 and 23 nor- '=mally urges them into .contactive engagement with the adjacent surfaces surrounding the apertures ZiJ-andZI respectively; If desired, the spring wres- 20 and 2'l, and are further so designed as to be of sufiicientstrengthrwhen dry, toresist the tensionof the spring 25.

r a It is also noted that the -members22 and 23 are of such size as to be slightly spaced from thewall surroundingthe chamber A.

of the member 23 and the surrounding wall of, the chamber A. From the said chamber A the sages for the travel of the air from the tube It) into the chamber A. It is noted that the upper portion of theextension 50 is provided with a horizontal cross-drilled opening 55 communicating with the aperture to complete the air passageway from the chamber A to the aperture 20. When the bottom grooved surface of the extension 58 is dry, a suction may be created to drawfluid into the pipette l0.- When the said fluid contacts the grooved surface of the extension, the greatly constricted passage air will continue to be drawn into the aperture 20 via the space between the edge of the member 22 and the surrounding wall ofv thefchamber A and in the interstices between the roughened sur face of the member 22 and the adjacent surface of the shank I50. If the members 22 and 23 are sufliciently porous, air will also travel directly through the material of the said members 22 and 23. To permit the free passage of such; air

presented by each individual groove acts as an effective barrier to the flow of the fluid. The

- viscosity of some fluids will prevent it from enthrough the members 22 and '23 I provide apertures 29 and 3D in the discs 26 and 21, respectively, as shown. 1

After an interval of time if the suction is continued fluid will be drawn into the pipette H) to fill the same, after which it will be drawn up into the aperture 23. At this point the fluid will contact and be absorbed by the mat 23' to become wet and soft and thereby cause the roughened surface of the said members 23 to collapse under the tension of the spring and to appear as shown in'Fig; 3 of the drawing. Thus a smooth soft seal will be provided against the aperture 2| to prevent the fluid from rising any further.

against the aperture 20.

Any suitable type of material having the above described characteristics may be employed for the members 22 and 23. One such material A similar action will occur with the member 22 to present a smooth soft seal which I have found to be highly satisfactory is asbestos paper. Y

The wet members 2?. and 23 may be readily replaced by dry pads by unscrewing the mouthmy invention may be satisfactorily accomplished without the use. of pads 22 and 23 and the spring 25.

One such modified form, shown in Fig, 4, comprises a batch of glass wool 4!] substantially filling the chamber A and overlying the apertures 20 and 2!. When dry, the glass wool 43, being porous, will permit the passage of air therethrough in its travel from the tube 10 to the aperture 28. When the fluid is brought into contact with the glass wool) it will enter into and fill up the interstices thereof to block the passage of the liquid therethrough.

In Figs. 5 and 6, instead of the glass wool 40, I provide an integral extension on the threaded shank I50, which is slightly smaller in diamethe pads 22 and 23. The height of the extension is substantially the same as that of the chamber A, so that the bottom surface of the extension is in firm contact with the surface surrounding The bottom surface of the exthe aperture 2|. tension 50, overlying the aperture 2| is provided with a series of fine grooves 5| to provide pass .tering the fine grooves 5|, while with other fluids thegrooves willlslowly fill up, to seal the aperture 2| and thus prevent fluid from being drawn up into the aperture 20. To provide greater efliciency-forthe action of the grooved extension 50, a central recessed area 52 may be provided in the bottom surface thereof directly overlying the aperture 2! and communicating with the grooves 5|.

It will thus be seen that there is provided a A device in which the several objects of this invention are achieved, and which is well adapted tomeet the conditions of practical use.

As various possible embodiments might bemade of the above invention, and as variouschanges might be made in the embodiment above set forth, it is to be understood that all matter herein set forthor shown in the accompanying A safety device for pipettes or the like comprising an attaching member provided with a mouthpiece and adapted to be attached to one end of said pipette, a chamber in said attachmg member, a first aperture in said attaching member communicating with said chamber and with said pipette and a second aperture come municating with said chamber and extending-v through said mouthpiece so that a suction may.

be created in said pipette to draw fluid therein by withdrawing air from said second aperture and means for preventing said fluid from entering said second aperture.

2. A safety device for pipettes or the like comprising an attaching member providedwith a mouthpiece and adapted to be attached to one member communicating with said chamber and with said pipette and a second aperture communicating with said chamber and extending through said mouthpiece so'that a suction may be created in said pipette to draw fluid therein by withdrawing air from said second aperture and means for preventing said fluid from enter- I ing said-second aperture, said last named means comprisinga member in said chamber having a surfacethereof overlying said first aperture, said surface-being roughened and so arranged that when dry air will be permitted to flow into said chamber through said first aperture and'when 3. A safety device for'pipettes or the like com-' prising an attaching member provided with a mouthpiece and adapted to be attached to one end of said pipette, a chamber in said attaching in'emben a first aperture in said attaching mem-.v

ber communicating with said chamber and with said pipette and a second aperture communicating with said chamber and extending through said mouthpiece so thata suction may be created in said pipette to draw fluid therein by withdrawing air from said second aperture and means for preventing said fluid from entering said second aperture, said last named means comprising a member in said chamber overlying said first aperture, said last named member being of porous nature so that when dry, air will be permitted to pass therethrough from said first aperture and into said chamber and when wet will seal said first aperture from communication with said chamber.

4. A safety device for pipettes according to claim 2 in which said member in said chamber is resiliently urged into overlying relationship with respect to said first aperture.

5. A safety device for pipettes according to claim 2 in which a second member is provided in said chamber, said second member being similar in function and design to said first member in said chamber and adapted to overlie the said second aperture.

6. A safety device for pipettes according to claim 2 in which a second member is provided in said chamber, said second member being similar in function and design to said first member in said chamber and adapted to overlie the said second aperture and a spring in said chamber interposed between said first and second members to normally urge said first and second members into overlying position with respect to said first and second apertures respectively.

'7. A safety device according to claim 2 in which said member in said chamber is made of asbestos paper or the like material.

8. A safety device according to claim 1 in which said means for preventing the fluid from entering said second aperture comprises a member in said chamber having a hard rough surface of such nature that when subjected to the action of a fluid it will soften and collapse under light pressure.

9. A safety device according to claim 1 in which said means in said chamber comprises glass wool or the like material.

10. A safety device for pipettes or the like comprising an attaching member provided with end of said pipette, a chamber in said attaching member, a first aperture in said attaching member communicating with said chamber and with said pipette and a second aperture communicating with said chamber and extending through said mouthpiece so that a suction may be created in said pipette to draw fluid therein by withdrawing air from said second aperture and means for preventing said fluid from entering said second aperture, said last named means comprising a member in said chamber having a surface thereof overlying said first aperture, and a second member in said chamber having a surface overlying said second aperture, said surfaces oi said first and second members in said chamber being hard and rough and of such nature that when subjected to the action of a fiuid they will soften and collapse under light pressure to seal said first and second apertures from communication with said chamber.

11. A safety device for pipettes according to claim 2 in which a second member is provided in said chamber, said second member being similar in function and design to said first member in said chamber and adapted to overlie the said second aperture and a spring in said chamber interposed between said first and second members to normally urge said first and second members into overlying position with respect to said first and second apertures respectively, the opposite ends of said spring being fixedly attached to washers which in turn contactively engage said first and second members in said chamber.

12. A safety device according to claim 1, in

which the means for preventing the fluid from entering said second aperture, comprises a series of fine capillary grooves formed between a pair of opposed surfaces in said chamber.

13. A safety device according to claim 1 in which the means for preventing the fiuid from entering said second aperture comprises a member in said chamber, integral with said mouthpiece and having a surface thereof overlying said first aperture, said last named surface comprising a series of fine grooved passageways for the purposes set forth.

WADDY T. MATHIS. 

